1. Field of the Invention
The invention relates to a power supply device, and more particularly to a power supply device which monitors power of a coin battery of a main system and provides backup power to maintain data in a CMOS storage area on a system chip when the power of the coin battery is insufficient and the coin battery is taken out to be replaced by a new one.
2. Description of the Related Art
Generally, a coin battery is disposed on a main board of a computer apparatus. When the computer apparatus is powered off (at this time, no stand-by power and no normal power is provided to the computer apparatus), the coin battery provides power to maintain data in a CMOS storage area on a system chip. Thus, when the computer apparatus is powered off and the coin battery provides no power, the data in the CMOS storage area on the system chip is lost because there is no power to maintain the data. When the computer apparatus is powered on at the next time, a user has to re-adjust the time of the main board and re-load a BIOS optimal setting to the computer apparatus. Current techniques provide a monitoring circuit to monitor power of the coin battery. Before the power of the coin battery is consumed completely, the monitoring circuit reminds the user to replace the coin battery with a new coin battery. However, in the process of the replacement of the coin battery, the data is lost because there is no power to maintain the data.
Thus, it is desired to provide a power supply device which is capable of monitoring power of a coin battery and providing backup power to maintain data in a CMOS storage area on a system chip when the coin battery is replaced by a new coin battery.